1
REMARKS
ON THE
DRAINAGE OF BOMBAY,
13 Y
WILLIAM SOWERBY, ESQ., O.E. F.G.S., &c.
iombaji:
PRINTED AT THE
EDUCATION SOCIETY’S PRESS, BYCULLAEEMAEKS
ON THE
DRAINAGE OF BOMBAY.
Captain Tulloch having been recommended, by the Secretary of
State for India, to report on the Drainage of Bombay, the Justices
very readily and properly availed themselves of his services—and
had Captain Tulloch confined himself simply to reporting on the
Drainage of Bombay, the writer of this would probably not have
again intruded his opinions upon the subject; but he has appended
another Report on a Memorandum on this question, prepared some
months ago, and consequently a few remarks in reply may not be
inappropriate, more especially as Mr. Arthur Crawford, the Muni-
cipal Commissioner, seems exceedingly anxious that the matter
should be well and thoroughly ventilated.
It may be remarked that Captain Tulloch has had the advantage
of having unrestricted access to all the Papers, Plans, Estimates,
and documents of whatever kind that have been previously prepared
and written on this question; and considering the recent experience
he gained while reporting on Madras, and the still later information
obtained in Europe, where he had been specially deputed to examine
this and cognate subjects, it might naturally be expected that his
Report on Bombay would have been not only very complete, but
thoroughly satisfactory and conclusive. The object of these remarks
is to examine how far these expectations hav'e been fulfilled.
First, as regards Captain Tulloch's own project, he tell us, that
until the publication of Mr. Rawlinson's last Report in January 1868,
the prevalent idea in the Town seemed to be that the Sewage should
be discharged into the Harbour. From what source Captain Tul-
loch obtained his information as to the “ prevalent idea17 about the
1	« d4
drainage, it would be difficult to say. It is true that two or three
projects may have been prepared haying outfalls into the harbour, but
the■“ prevalent idea” always has been that Bombay could never be
properly drained, except by some extraordinary means not yet dis-
covered—and Captain Tulloch has probably inadvertently adopted
this idea; for the means by which he proposes to drain Bombay,
when carefully examined, are certainly very extraordinary indeed,
and such as few Engineers who understand the subject would be
prepared either to recommend or carry out.
It may be worth while mentioning, however, that so long ago as
1863, the writer, at an interview with the late Governor of Bombay,
Sir Bartle Frere, pointed out that the proper and best way of drain-
ing Bombay was by carrying the main drain to the Northward, right
through the heart of the island: and about the same period, he also
explained his views to the present Municipal Commissioner, Mr.
Crawford, who was, however, at that time otherwise employed, and
probably did not pay much attention to the subject.
A mere glance at the Model Map of the Island which the writer
has now prepared, indicates clearly enough the proper line of drain-
age, and notwithstanding all that Mr. Rawlinson or Captain
Tulloch has said, or may say upon the subject, it is quite evident
from an inspection of the Contour Map, that a small portion of the
drainage of Bombay must always inevitably find its way into the
Harbour. To attempt to divert it into the opposite direction, and
there pump it into the sea or anywhere else, would not only involve
great expense in itself, but would make the drainage of the other and
larger portion of the Island a very great deal more difficult and
costly to deal with, involving powerful Pumping Engines, and other
means and appliances at great outlay; and this is exactly what
Captain Tulloch proposes, and consequently he gets himself into
difficulties which do not naturally exist.
It is somewhat curious to observe that, while Captain Tulloch
himself condemns and points out the mistake that would be made in
any attempt to drain the Island ftom the Flats into the harbour in
the direction of Colaba—he should fall into a mistake quite as great^
by proposing to carry the drainage of the Fort to the Flats, across
the ridge which runs along the Esplanade; thus making the Main5
Drain unnecessarily long by upwards of a mile, and also increasing
tlie depth very considerably. The natural outlet for the drainage of
the Fort and the Esplanade, is into the Harbour* The advantage
supposed to be gained by Captain Tulloch is the removal of the
Sewage from the Harbour; but is not this much more than counter-
balanced by the nuisance of conveying the sewage of the Port right
through the heart of the best part of the town, carrying with it its
poisonous effluvium all along the route ? It would indeed be much
better to get rid of it at once into the Harbour, where it would be
diluted with plenty of sea water. This Fort sewage, be it remem-
bered, is derived from but a very small portion of the Town and
Island, and it is quite a different matter from that of taking the
whole sewage of the City into the harbour at one point, which would
be most objectionable.
Captain Tulloch says that the effluvium from the present main
Drain of the Fort is at times very great. This can only be due to a
deficiency of water for flushing, and if kept well flushed, the
nuisance would disappear; for every body knows there is no better
deodorizer tha,n plenty of water, though Captain Tulloch very
dogmatically gives his opinion to the contrary.
But if the sewage in the present main drain of the Fort is some-
times a nuisance, then how much greater an evil would it be to
convey this filthy matter along a drain right through the heart of
the City on to the Flats, to poison the atmosphere in its course ? for
in spite of the best constructed stench-traps, it will be sure to do
this. By far the most sensible plan would be to double or treble
the water supply into the old drain and thus get rid of the sewage
by a process at once simple and effective ; and if Ihe discharge be
effected into the «harbour at a suitable time of the tide, it need never
be a serious nuisance; if it should be so, it will be through neglect of
the most ordinary precautions.
Captain Tulloch endeavours to make this a much greater bugbear
than it ever need be, when he talks of the sewage of a City containing
two millions of people in 50 years time, giving 4,400 cubic feet of
sewage per minute night and day;—this would unquestionably be a
tremendous evil, one so great that, as Captain Tulloch justly remarks,
“wherever on the coast such a large quantity of filthy matter is
2	sd6
discharged, I maintain tliat it will make its presence known, indeed
the most serious consequences might arise&c., &c. . Just so ; and
yet most strangely enough Captain Tulloch himself proposes to
discharge all this sewage at his main outlet in Love Grove, and
more remarkable still, to make a People's Park close to the outfall!!
but more of this by and bye.
Captain Tulloch observes truly that it is its magnificent
Harbour that gives Bombay its importance in India, just as the
Thames gives London its importance in England; but if the
sullage of a huge city like London does not poison the Thames
when cast into it well away down the river within the influence of
the tide, surely a few hundred tons of well-diluted sewage from
the Fort can do but little harm in a harbour like Bombay, with the
whole force of the Indian Ocean rolling directly into it from the
South Polar regions twice a day, and with a tidal rise of from 10 to
15 feet. It is only when the entire filth of the city is thrown en
masse into the harbour, or on any of the part of the coast, that
danger is to be apprehended; and yet this is just what Captain
Tulloch himself advises—only, as the lawyers say, “ he changes the
venue ” to the other side of the Island.
Captain Tulloch next proposes to set* aside all sanitary consider-
ations, and to decide the question on purely Engineering grounds,
and he refers to a map of the Island with levels marked1 thereon. In
order more clearly to understand this map, the writer has coloured
it as a model Chart, and it is then that the true topographical
character of the Island is clearly seen. The low-lying ground
occupies two-thirds of the Island, and has evidently at no remote
period been covered by the sea, surrounded by Islands, these last
being Malabar and Cumballa Hills, also some high ground near
Love Grove, and from Worlee to Mahim on the west, while on the
east there is Colaba, the Fort and Esplanade, the Nowrojee and
Mazagon Hills, and a ridge more or less continuous up to Sion* An
irregular branch of the low-lying ground continues in a south-east
direction from the Esplanade, the latter being high ground which
distinctly divides the Fort from the Flats by a broad belt of elevated
land. On purely Engineering grounds then, it is very evident that
the proper and natural outfall for the portion of the city near and7
including the Fort, is clearly in the direction of the Harbour, and a
line drawn from about the Carnac Bunder or Mallet Basin across
by E etwady to Gowalla Tank, opposite Malabar and Cumballa Hills,
would nearly divide the two drainage areas. All land to the south of
this should, on Engineering grounds, be drained either into Back
Bay, or into the main Harbour—this would embrace a very large
proportion of the land already^ built upon in Bombay. •
In executing any new drainage works, it is possible that some
portion of the area above indicated might be best drained in the
direction of the Flats, the Esplanade being made the neutral ground
between the two drainage areas, but no one wpuld surely propose to
drain the ground on the east side of Nowrojee Hill, between it and
the Elphinstone land into the Flats, so |hat practically the difficult
part of the drainage of Bombay resolves itself into a question of the
drainage of that immense area called “the Flats ”
Captain Tulloch seems to think that even in the details of his main
sewer, he has selected the best line, but this is by no means the
5as%—for if we were to adopt his method, the most direct line is
not by Ketwftdy, but considerably to the northward even of the
existing sewer, where there is a valley leading much more shortly
on to the Flats, and by which route, the extraordinary crooked and
objectionable bends he adopts would be entirely avoided, and the
sewer wouldtriin along ground lower than what he proposes* for it
is only 54 and 55 feet above datum, as against 58 and 59 feet, so
that taking Captain Tulloch on his own ground, it is evident he
has neither adopted the straightest and most direct line, so as to
obtain the best gradients, nor does the route he proposes follow
the lowest ground, nor the proper valley line leading on to the
Flats.
Captain Tulloch, after remarking on the facility of constructing
the drains along the Flats owing to the nature of the soil &c.,
observes “ that perhaps the greatest of all advantages will be of a
prospective* nature/* and further on he explains that these great
prospective advantages will be obtained by the feasibility of carrying
a drain from a mile beyond Parell to the Love Grove Pumping
Station. Surely Captain Tulloch would never attempt to bring the
whole of the sewage and filth from a mile beyond Parell to Love8
Grove, in order that it might be pumped up there, when there is a
much nearer, more convenient, and suitable outlet close at hand in
the ópposite direction ! The proposition to bring the whole of the
drainage of the Fort on to the Flats is bad enough, but to bring the
drainage from a mile beyond Parell into the same place for the pur-
pose of being pumped into the sea there, does appear a very round-
about way ft* proceeding; and yet, fprsooth, Captain Tulioch calls
this one of the “greatest prospective advantages.” Surely he cannot
have well considered his project—the carrying of a drain along the
valley of the Flats is right enough, but why it should find an outlet
at Love Grove is inexplicable, unless it be to give the adjacent Park
which Captain Tulioch proposes, the benefit of additional sewage for
irrigation.
Captain Tulioch tells us that he has been given to understand that
the direction in which the Town has always shown a tendency to
spread is towards the Flats. This fact, one would have imagined was
patent to all, considering that it is the only direction in which there
is vacant space for building upon. It is true that some few years
ago there were several gigantic projects for reclaimingCrom the sea
Back Bay and other localities;—these have, however, been wisely
abandoned as impracticable, after as much money has been spent on
them as would have rendered Bombay one of the most splendid cities
in the world. But it is very difficult to follow Captaip Tulioch in
his train of reasoning why the Drainage of Bombay should all be
collected on the Flats because of the Town having a tendency to
spread in that direction. Surely according to his own showing, the
drainage should be carried as far away from where the town is likely
to be concentrated, as is practicable ; nor is it quite clear why, because
the main sewer passes through the Flats, that therefore the most
rapid falls could be secured for the street drains, for when the
Flats are built upon, then the streets will all be in low lying ground,
as, at the broad part of these Flats, the low ground occupies three-
fourths the width of the whole Island, and at the narrower part to
the northward, the width is about one-half.
Captain Tulioch says that whatever outfall may be selected, it is
physically impossible to discharge the sewage without the help of
pumps. This assertion is made with such emphasis, that it would9
appear to be almost useless to attempt to controvert it;—but let us
examine the facts, as it is merely a question of figures and levels,
with nothing mysterious about it. Captain Tulloch appears to take
a delight in making unnecessary difficulties, and then proposing
unusual means for overcoming them; and his plan of requiring
powerful pumping engines, is an example of extraordinary means
for overcoming difficulties of his own creation, and which do not
uaturally exist; and the remedies he proposes are quite uncalled for.
Captain Tulloch first speaks of the necessity for engine power to
pump away the. sewage, and then without waiting to settle this
point, he proceeds to give a description of the Plats, which he cor-
rectly enough says “ is swampy ground and productive of much un-
healthiness, and that therefore their reclamation is very desirable, and
would have a most beneficial effect as regards the sanitary condition
of Bombay.” All this every body knows and admits, but the drain-
age of the existing town, and the reclamation of the Plats are two
distinct questions.
As the Plats are already surcharged with moisture for nearly half
the year, it would be very desirable, if possible, not to carry the
drainage of the town in that direction, or, in any case, to divert as
much as possible of it, and also of the surface water, in some other
direction, so as to limit the quantity of moisture in a low-lying dis-
trict like the*Plats. But Captain Tulloch contrives to mix up the
two questions in such a way that it is impossible to tell what propor-
tion of his project is strictly one of drainage, and what part is intended
as Eeclamation work; this is especially the case as regards the pump-
ing engines.
Captain Tulloch tells us that the level of the floods on the Flats
on the 9th of August, 1868, was 54*50, and as part of this ground is
only 47 to 48, there must have been 6*50 to 7*50 feet of water on
them. He also states that in parts of the Town, the flood waters
stood at 58 above datum, or 3*50 above the surface of the floods in
the Plats. Captain Tulloch does not say in what part of the town
this occurred; but it is evident it had no direct communication with
the Plats, or the water could never have stood at so high a level; it
must therefore have been an isolated basin. It is strange, however,
that the Contour Map shows no such basin in the town.
3	sd10
Captain Tullocli also says tliat before the Breach Vellard was con-
structed the Town was not liable to floods by rain, because the rain could
always escape into the sea. The Breach Vellard has kept the sea
out, but it keeps the rain in , Now the remedy for this would appear
simple enough, namely, the construction of sluices of sufficient capa-
city to allow the rain water to find an exit with open channels in the
proper direction across the Flats up to those sluices. But Captain
Tulloch is not satisfied with this—he persists in proposing to rebuild
the old main drain, and carrying it with a greater slope up to the
outlet at Love Grove. The bottom of this drain when re-constructed^
will be between 4 to 8 feet below low water, and, consequently, the
whole of the water which comes down this drain must be pumped
up into the sea. If the flood waters found their way out to sea
before the construction of the Breach Vellard, and if sluices of sufficient
capacity are constructed so as to allow the exit of the floods as
before the Breach Vellard was made—what possible reason is there
for building a covered-in drain for carrying off these floods, and put-
ting the drain 4 to 8 feet below low water mark ? and of what possible*
use can pumping engines be to pump up the flood waters from such
a drain, provided sluices are constructed of ample size to allow the
water to flow out to sea, as it did prior to the building of the Breach
Vellard ? Is not then the proposed expenditure of Rupees 7,65,475
or with contingencies equal to	„	76,547
8,42,022
about £85,000 sterling, for the extension of the present main drain
a useless waste of money ? and if to this we add a moiety of the
cost of the pumping engines, or 4| lacs more, then there is ^ .total
cost of nearly £130,000 sterling, which, according to Captain Tul-
loch*s own showing, was not required prior to the building of the
Breach Vellard, and if by the construction of sluices the outlet is
restored to what it would be equivalent to in its original condition,
then this outlay must be quite unnecesary now.
There are probably some in Bombay who remember the Fleet
Ditch in London. This was originally an open water course, and was
subsequently covered over as a sewer similar to the old Main Drain
in Bombay, with a sluice trap at the outfall into the Thames to11
prevent tlie tidal water entering the ditch. If we suppose that any
person had proposed to lower the outfall of this ditch, near
Blackfriars Bridge, to 7 or 8 feet below low water mark, and tlien to
erect a steam pumping engine to raise the water into the river,—
such a proposition would at once be pronounced as absurd, yet this
is exactly what Captain Tulloch proposes to do with the old drain
at Love Grove.
In Surat there is a very similar water-course which is about to be
dammed up, to keep out from the City the floods of the river Taptee,
with sluice-gates to allow the rain water to pass away, as soon as the
river has subsided. What would have been thought of this project
if, instead of building a dam and sluice-gates, it had been proposed
to lower the bed of the stream 7 or 8 feet below low water-line, and
then to erect powerful engines to pump the water into the Taptee ?
yet this is precisely what Captain Tulloch proposes at Love Grove.
Captain Tulloch states that the area which drains on to the Flats
is 16 square miles,—this is equal to a length of about 6-| miles by
a width of 2J miles. On measuring the area from the Contour
Chart, which clearly shows the portion which slopes towards the
Flats, the area is not 16 but 10 square miles, and it is doubtful
whether it would be quite as much as 10 square miles if the area
were more carefully calculated, so that we here have an error of
three-eighths in his calculations of the drainage area which has to
be dealt with on the Flats. Of course Captain Tulloch includes in
his calculations the area of the Flats, which in themselves are about
four and a half square miles ; so that the drainage area which he has
actually to deal with, is not 16 square miles as Captain Tulloch
states/but 10 square miles less the area of the Flats themselves,
reducing the space to lie treated as drainage surface to 5J square
miles, and the reclamation of the Flats to 4 J square miles.
Captain Tulloch tells us that the total quantity of water which fell
on the 9th of August 1868, was 14 inches in 24 hours; which, over
the whole area of the Island would be equal to 520 millions of cubic
feet, or about 14J million tons of water: and he then proceeds to
state that this immense body of water can be got rid of in 24 hours
by the sluices and pumping engines he proposes to erect.12
Let us first accept Captain Tulloclr’s statement as regards the
520 millions of cubic feet in 24 hours, and see how far his intended
sluices will discharge this quantity of water. Captain Tulloch omits
to show how the water is to travel to these sluices, we therefore pre-
sume, he means it to get there by the existing natural channels. The
old main drain can be no help whatever, as it is too far below what
the level of the sills of the sluices must be.
Assuming then the sills of the sluices to be at the same level as the
lowest ground in the Plats, namely, 47 above datum, and the top at the
highest level of the floods in the Flats to be 55*50, this would give
an opening of the difference of feet, or 3 sluices 120 feet each=
360 X or an area of 2,700 square feet; so that if the sluices were
kept constantly open with a head of water of 1\ feet, moving at a velo-
city of 2\ feet per second, the whole 520 millions would be discharged
in the 24 hours; but the aperture of the sluices would be constantly
diminishing by the rising of the tide, and the number of hours it could
be open would also be reduced by the same cause; so that the aver-
age height by this would be lessened to, from feet to the difference
between the level of the sills 47, and mean sea level, which is 50, or
only 3 feet. But even this head of water would not be a constant
average, for it would be diminished by the gradual falling of the
floods in the Flats; and this diminution would be about 1J feet, so that
with this aperture and average head of water, and the whole sluices
entirely closed by the tide for 12 hours out of the 24, the water
flowing at a speed of 10 feet in a second, would discharge 245 mil-
lions of cubic feet only, or about one half ;—but with such a head of
water, the velocity would not be ten feet in a second, nor anything
like it.	#
Captain Tulloch, it is true, proposes to assist these sluices by means
of the pumps; and he provides for 500 horse engine power, which
would be equal to the raising of 1,324,800 tons 8 feet high in a day.
But as only one moiety of this Engine power can ever be avail-
able for pumping the floods, it would only relieve the Flats of about
662,400 tons of water in the 24 hours, or if Captain TullocVs state-
ment is to be accepted, which gives 520 millions of cubic feet or 14^
millions of tons of water, then it will be only 4 per cent, of the flood13
water, that can thus be removed, and this at an expenditure of
£45,000 sterling.
But Captain Tulloeh is altogether in error as to the quantity of
water which collects on the Plats, and which has to be dealt with.
If he had carefully studied the various Reports on Drainage that
have been drawn up during the last twenty years, and more particu-
larly those of the Metropolitan Commissioners of Sewers, he would
have known that after a series of numerous and most careful
experiments had been made, it was ascertained that the proportion of
rainfall which found its way into the water-courses during the
heaviest rains was something short of two-thirds of the actual
quantity which fell, and that more than one-third never found its way
into any drain, but passed off by absorption aird evaporation. These
experiments were made and repeated in various localities where the
houses were covered with slates, and where the water-spouts were
perfect, and the streets either paved or flagged. Now, if less than
two-thirds of the rainfall found its way into the water-courses under
*suc^ conditions in London, where the climate is comparatively
humid, what proportion would find its way through the imperfect
channels, and over the absorbant soil of Bombay into the Plats ? If
Captain Tulloeh had set himself first to solve this important problem,
which he could easily have done, he would have saved himself the
Herculean task of getting rid of 520 millions of cubic feet of water in
24 hours; and it is herein that Captain Tulloeh fails most completely.
The area which drains into the Plats, it has been shown, is not 16
square miles, but only 10, or about 5-8ths, so that the quantity of
water he assumes, namely, 520 millions of cubic feet, should be
reduced to 325 millions, and according to the experiments in
London, only two-thirds of this 825 millions would find its way to
the Flats, or 217 millions of cubic feet, or about 6 millions of tons.
It has also been shown that the area of the Flats subject to floods
is 4£ square miles, or 2,880 acres, and the average depth of water
over this area during the floods was about 24 inches. The calculated
quantity would thus be between 6 and 7 millions of tons of water
to be dealt with, instead of the 14^ millions of tons according to
Captain Tulloch^s statement. These are simple arithmetical calcula-
tions which any one may verify, and are here recapitulated in order
4	sd14
to show the very little dependence that is to be placed on the data
supplied by Captain Tulloch.
There are portions of Captain Tulloch^s report, which, when we
come to examine them in detail, are quite incomprehensible; namely,
where he says, that it will never do to let the Town itself get
swamped, though the Flats may lie under water for a few hours.
He here evidently refers to that portion of the Town in which he
says th^ floods stood at 58 above datum. What part of the Town
became filled with water to this height while the floods stood
at only 54*50 on the Flats, he omits *to mention; for a simple
connection between the locality in the town that was flooded and
the Flats, would at once have caused the water to sink to the flood
level on the Flats; and as the water from the town must cross the
Flats somehow to get to the pumping station, therefore, when a
channel is made to the Flats from the part referred to, which was
under water, the inundation would at once subside without the aid
of any pumping engines whatever ; unless Captain Tulloch means to
carry that water underground by his projected continuation of the
old main drain, which main drain would be covered with many feet
of water all along the Flats. This is certainly one of the most curi-
ous and wonderful propositions ever propounded by an Engineer.
Probably Captain Tulloch has never known a drain constructed in
this way. Jf he had been at Broach in the monsoon of 1867, he
would have seen just such a one as he proposes, torn up by ihe
floods, and utterly destroyed.
It is suspected that at the part of the Town where the flood line
stood at 58, it was owing to downright neglect of all ordinary precau-
tions. Some few years ago the n^ain road in Surat was rendered im-
passable during the monsoon, and on visiting it the first plunge of
the horses was up to the girths in mud. On examining the ground
it was discovered that a culvert through which the floodwater should
pass, was choked up to the roof; and no doubt something very similar
was the cause of the flood in the higher portion of the town of
Bombay. '	.
There is still a further point in Captain Tulloch* s Report relating
to these floods, which is quite inexplicable. He states at page 26,
that, as the population and town increases, the Project will become15
more perfect,, and a flood be rendered quite impossible. Now what
can be the meaning of this ? Does it mean that as the Island becomes
covered with new streets and buildings, the floods will not find their
way into the lowest parts of it, or does it mean that the engine-power
required to lift the increased quantity of sewagg will be sufficient
also to lift the flood waters ? Captain Tulloch is exceedingly obscure
as to the exact quantity of flood-water the engines will help to
eject in the first instance. He chiefly relies on the proposed sluices.
He provides 500 horse power engines for the present population
of one million people; we may therefore assume that 1000 horse power
will be required for 2 millions 50 years hence, and as the average
height the water would have to be raised is 8 feet, then the 1000
horse power is equal to something over 2^ million tons in the 24
hours; but as a moiety of this power can only be available, it would
be equal to 1^ million of tons. What then becomes of the 14\
millions, he says collect on the Flats ? or the still less quantity of 6
millions, which is probably nearer the true quantity ?
Having said sufficient to show that the whole of Captain Tulloch* s
statements and calculations as regards the floods are utterly unreliable,
let us now examine his proposed system of sewerage. It has already
been pointed out that the line of the new main sewer he adopts, does
not follow either the lowest valley or the most direct route to the
Flats; on the contrary, the valley he selects is at least font feet higher
than the one further to the northward, besides, his line of drain is
exceedingly crooked, with bends in some places quite at right angles;
and therefore such as should be avoided. It has also been shown
that by Captain Tulloch’s plan, he unnecessarily increases the length
of his drain by 1£ miles, and as the fall given to this part is 4 feet
per mile, the depth is increased by 5 feet 4 inches, or say 5 feet. The
adjacent land where the main drain should be first commenced, is 68
to 72 above datum, the sole of the drain might therefore be at 57. The
entire distance to the Love Grove sluices is miles, and if we allow
3 feet for the first mile, and 2J for the remainder, as proposed by
Captain Tulloch, we have an entire fall of about 8*6, which would
allow the sole of the drain to be 48*5, or 3 feet 6 inches above low
water neap tides', and nearly 6 feet above low water spring tides,
which would be sufficient to enable the whole of the sewage to be16
flushed into the sea, without any pumping engines whatever, pro-
vided there was an ample supply of water for flushing; and without
this, no sewers of whatever size, shape, or level, can ever act properly
or be kept clean.
But there is no particular reason why the outfall of the sewage
should be placed at Love Grove, except that there already exists a
sort of outfall; the new one might just as well be half a mile nearer
to*Mahaluxmee, and thus a foot and a half more in the levels would
be gained by reducing the length of the main drain. This additional
foot and a half could be used either for raising the sole of the sewer,
or increasing the fall. If the sewage has to be cast into the sea, it
can make very little difference at what point it is so, only there must
be plenty of water for flushing.
When Captain Tulloch has to deal with the immense quantity of
flood-water, amounting as he states to 14£ millions of tons, he pro-
poses to get rid of it in a day; but when he has to deal with some-
thing less than 90,000 tons of sewage, he proposes large steam'
pumping engines at a cost of £90,000 sterling. The reason, of
course, for all this great expenditure is that the outfall is carried to
such a low level, that it is necessary to raise it again in order to get
rid of it. He tells us that it is a physical impossibility to dispose
of the sullage without pumping, whereas, the levels show that it is
nothing of tj|e kind, but that there is an ample fall and a sufficient
head to allow it to pass off by means of gravitation only, but there
must be a sufficient supply of water for flushing, and without this
even the pumping will be an utter and complete failure; besides, if
pumps be adopted, it will be an object to reduce the flushing to a
minimum, in order to curtail the work to be done by the engines.
Having disposed of Captain Tulloch*s main drain from the south,
let us now revert to the one he ultimately proposes to bring from
the north, a mile beyond Parell, and which he tells us offers cc the
greatest advantages of a prospective nature.” A mile beyond
Parell to the north gives about three miles from the outfall at Love
Grove, and the ground at that point is low-lying, above 52 above
datum, and if we put the sole of this drain at its commencement at
the same depth below the surface that Captain Tulloch puts his drain
at the Fort, namely 13 feet, then the sole would be 39 above datum,17
an|| if we give it the same inclination as he does his main sewer,
namely 3 feet for the first mile, and 2 feet 6 inches per mile for the
remainder, then there is a total fall of 8 feet to be deducted from
the 39 feet, which makes the level at the outfall to be 31 feet above
datum, or 6 feet lower than the level of the outfall of his main
sewer from the Fort. This increases the average left from 8 feet
to 14 feet, and will therefore require a separate system of more
powerful pumping engines—a very great “ prospective advantage,*'
certainly! ! !
It is not intended to ignore altogether the advantage of pumping
engines, when found necessary, but it is contended that they are not
required. It is not impossible that there may be one or two low
lying localities where a small pumping engine might be introduced
with advantage; but this must be for a comparatively small area,
and certainly not for the whole drainage of the City of Bombay. If
pumping is to be applied, it would be milch better employed to fill
the sewers with water for cleansing and flushing, than for emptying
the^n.
The perfection of any system of Drainage is one that takes advan-
tage of every facility which the contour of the ground naturally
offers, dividing the space into drainage areas, having reference to
their elevation, and treating those parts which are unusually low in
an exceptional manner. Captain Tullochhas evidently rfot carefully
studied the contour of the Island; he has apparently had but one
prominent idea, namely that of carrying the main drain along the
low-lying ground, and making the whole of the rest of the Island,
no matter how elevated, conform to his low-lying main sewer, and
the consequence is, he is compelled to adopt expensive pumping
engines to get himself out of the difficulty he has created.
•
One of the most prominent features in Captain Tulloclr’s system
of drainage, is the laying down of 70 miles of pipe drains; 15 miles
to be 12 inches diameter, and the remaining 55 miles of 9 inch
piping. This system of telescopic pipe drains is better known as
the “ Chadwick” principle, the original advocate of the plan being
Mr. Edwin Chadwick, of London. Whatever Captain Tulloch’s
experience on this point may be, we do not know, and he does not
tell us; but it is a well-ascertained fact that wherever these pipes
5	sd18
have been adopted in Europe as main drains, they have utterly
failed; as branches to houses they are most useful, but they %re
quite unfit for street drains. Perhaps Captain Tulloch has not
heard or read of the many important discussions that have taken
place on this very question, and the unanimity with which they have
invariably been condemned by every experienced Engineer whose
opinion was of any real value. Nor can Captain Tulloch be aware
<»f the terrible consequences that have ensued by the adoption of
these pipes, which have become choked up, and poisoned whole
lines of houses in London, Croydon, and elsewhere. If then such
a system of pipe sewers be unsuitable for Europe, they are much
more unfit for a climate like India; for, let Captain Tulloch be as con-
fident as he pleases, they will inevitably choke up, and in less than
12 months be rendered perfectly useless : yet upon this part of the
project, it is proposed to spend, with contingencies, 12 lakhs, or
about £120,000 sterling.
Assuming that these pipe drains are adopted as street drains,
which it is fervently hoped they never may be), there must be kepf
up a constant supply of water to flush them, and this constant supply
is doubly and trebly necessary, in order to keep them clean; yet in
no part of Captain Tulloch^s scheme is there any provision for
obtaining an adequate supply of water.
Captain Tulloch admits at page 30 that there is no doubt a great
scarcity of water at present in Bombay, yet strangely enough, he
never dreams of endeavouring <- to retain some portion of that 520
millions cubic feet of water which he says falls within the Island ;
on the contrary he proposes an expenditure of one hundred and
thirty thousand pounds, to get rid of it in 24 hours.
We now approach a branch of the subject on which it would have
been well if Captain Tulloch had been a little more decided, or at
least as decided as he is upon some other points of the question
under discussion. He is very clear as to the advisability of separat-
ing the rain water from the sewage, but he is most uncertain as to
the propriety of allowing the excreta to find its way into the drains.
It is very surprising to find him saying at page 30 “ that it really
does not matter for the purposes of this Report, how the excreta
is disposed of.^ This is a most singular conclusion to have arrived19
^^particularly wlien it is considered that one most important part of
his project is that of utilizing the sewage, while it is always supposed
that sewage is chiefly valuable owing to the excrementitious matters
held in solution and suspension, so that if these be kept away from
it, there remains only a quantity of diluted soap-suds and dish-wash-
ings, which can add but very little, if any thing, to the value of the
sewer waters ; and yet upon this part of the project, he proposes an
expenditure, with contingencies, of upwards of 20 lacs, or £200,000
sterling; and if the engine power be added to this, which, according
to Captain Tulloch will be necessary to raise the sewage over a
standpipe of 50 feet high, then the total will be about a quarter of
a million sterling. Surely Captain Tulloch can never seriously pro-
pose such an enormous expenditure, with such vague and unsatis-
factory prospects. Any project for the Drainage of Bombay without
some definitive plan for disposing of the excreta, is very much like
proposing to perform the play of Hamlet, and leaving out the princi-
pal character.
' At the best, sewage-irrigation is very problematical, and Captain
Tulloch ought to know well that it can only succeed where the soil
nnd other circumstances are decidedly favourable, or as the author
of “ Drley Farm” says, “ Chemical agriculture is expensive, and
though the results may possibly prove remunerative, still while we
&re kept waiting by the backwardness of Chemists, there must be
much risk in making any serious expenditure with such views.”
The very fact that Captain Tulloch mentions regarding Rugby
proves this; for the grass grown is evidently not suitable for making
hay, and so it has to be consumed on the spot, and the recent reports
of the London Sewage Company prove, if they prove anything, that
sewage-irrigation is not, and never can be a very profitable specula-
tion in the Essex and Plumstead marshes; and if money were never
so abundant (and it could not well be lower than it has been at 2
per cent.), capitalists would avoid any such speculation.
The original Sewage Manure Company of London, which was
formed more than twenty years ago, commenced with every possible
advantage that was desirable to make such a scheme profitable • and
successful. It had abundance of rich sewage at Counter's Creek, it
had a large tract of Market Gardens close by, and the gardeners20
availed themselves of the supply of sewage, as much as they cared
to take; yet with all these advantages it was a failure, as the writer
knows full well, happening to have some shares in the undertaking.
•
It has been wisely laid down in the Indian Railway Department
that nothing shall be sent out which has not first had a fair trial in
Europe, and in a question of this kind, it would be hardly prudent
to adopt a project which has hitherto proved by no means* success-
ful, more particularly as the humid and salt-batty Flats are the
worst places that could be selected; if there were any sandy, gravelly,
or arid uplands to irrigate, then success might not be so very doubt-
ful.
If the Municipal authorities have a superfluity of capital at their
disposal, which they wish to expend on Irrigation, they had much
better hand it over to Colonel Fife, who will doubtless be able to
show them a far more certain way of ensuring a profitable return for
their money, than that of spending it in a sewage-irrigation scheme
on the Flats of Bombay, for growing gigantic and unwholesome
vegetables.
Captain Tulloch, at page 29 of his Report, briefly refers to the
question of ventilation, but without getting beyond what he calls
the Charcoal system. He proposes to carry ventilating pipes up to
the tops of the houses. Sewers resemble in this respect the hold of
a ship, or the workings of a coal-mine, and they should be treated
in a similar way; there must be,r in addition to the charcoal “ upcast
shafts,” also “ downcast shafts,” for the admission of pure air, so &s to
prevent the accumulation of deleterious gases. A paper is herewith
annexed which was published by the writer in 1849, and it fully
discusses this question. An abundant supply of air is as necessary
to keep sewers sweet, as is a supply of water to keep them clean,
and herein is one of the great defects of Captain Tulloch's proposed
telescopic pipe system, which admits of no proper means of venti-
, lation; and the disastrous consequences that would arise from these
pipes for this reason, would be incalculable.
Captain Tulloch proposes to fill in all the existing open drains,
substituting his pipes. These open drains, though by no means
perfect, are readily come-at-able, so to speak, and are not likely to21
choke up, if an ordinary amount of attention be bestowed upon them^
whereas the pipes will require the most careful and unremitting
supervision ; besides, open drains have the advantage of a free circu-
lation of air, which pipes never can have. It might be advisable to*
cover over these open drains, but to fill them in would be a very
unwise proceeding, at all events, until the success of the pipes was
well assured. Dr. Thomas Blaney will possibly tell Captain Tulloch
something about the Infusoria that will be generated in his pipes,,
whereas, if the scavengers do their duty, and there is plenty of water,
the open drains can be kept perfectly clean, and free from filth and
nuisance. It is a very convenient doctrine to put the filth out of
sight under ground, but it is this which is to be dreaded, for when
put there and confined, it is much more liable to be forgotten and
to remain poisoning the surrounding atmosphere.
Captain Tulloch, after expatiating on the filthy and unwholesome
condition of the Flats, and condemning any attempt to raise them,
also recommending the irrigation of a portion of them on Mr. Raw-
lin$on's plan, with sewage of the City, curiously enough proposes to
carry out Mr. Crawford's scheme of converting them into a Public
Park for health and recreation. The idea of converting a part of
the Flats into a People's Park, is not per se a bad one; it is
when viewed in connection with his irrigation scheme, and
his outlet at Love Grove, that it seems strangely inconsistent,
and in fact, absurd; for does he not say at page 5 of his report that
“ wherever on the coast such a krge quantity of filthy matter is
discharged, I maintain that it will make its presence known, in-
deed the most serious consequences might arise/' &c. &c. Now by
puting this and that together, the only reasonable inference to be
drawn from it is, that the People's Park, which is intended for health
and recreation, will be close to a spot where the whole filth of the
city “ will make its presence known, and where the most serious
consequences might arise." It would therefore, according to
Captain Tulloch's own showing, be very undesirable to have this
People's Park close to the outfall of the concentrated main drainage
of Bombay, however desirable it might be in other respects. In-
dependently, however, of what Captain Tulloch says, the idea of
the Park being in such close proximity to the sewers-outfall, and the22
sewage-irrigated land, is palpably too gross an inconsistency to be
entertained.
Captain Tulloch instances the People's Park in Madras, which
he says was once a swamp, and a receptacle for the filth of the Town.
It ever having been a swamp, except possibly for a month or so dur-
ing the monsoon, is very doubtful; for a canal runs along the side
of it, and the ground is above the canal level; besides tke Coom
river is close *by, and Madras is almost as dry as the slopes of Vesu-
vius for 9 or 10 months of the year. But that it was a receptacle for
filth can easily be believed, for there used to be a similar receptacle
within a stone's-throw of Government House, which is reported to
have caused the death of one Governor, Sir H. Ward, from Cholera,
and which rendered the house untenable for many months, so that
His Excellency had to make a timely retreat to the country residence
at Guindy. Perhaps Captain Tulloch will be able hereafter to explain
this part of his scheme a little better.
Captain Tulloch omits to provide any sumpts or accumulating
reservoirs at his outfall, which will be necessary, nor does he ray
what he will do with the sewage during the monsoon, when it can
be of no use; but he tells us at page 19 that “if the sewage utiliza-
tion proves a failure, it can be discharged into the Harbour side
of Colaba” ! ! !—There is much in Captain Tulloch's project that is
remarkably curious, but perhaps this last idea of conveying the
sewage back to Colaba after it has been carried across the Flats to
Love Grove, is unique in Drainage Engineering, and requires no
comment.
Taking a summary retrospect of Captain Tulloch's Report, and
project, it amounts to this:—
He purposes to get rid of the surface Drainage by means of sluices
and the aid of expensive and powerful pumps, also by an extension
of the existing main drain, to be carried to a low level under water
during the floods: this at a cost of about 16 lakhs, or £160,000
sterling. But he provides no means of retaining any portion of the
immense body of water which falls on the Island, and which might
be kept for many useful purposes.
That he proposes a scheme of Town Drainage by means of a
main sewer, unnecessarily long, deep, and very drooked, together23
with 70 miles of branch pipe drains, which will be quite useless in
less than 12 months ; and this with the addition of the pumps, will
cost about 34 lakhs, or £340,000 sterling. But he entirely omits
to deal with the excreta, nor does he make any provision for extra
water supply for sluicing his drains and pipes, without which they
will be very much worse than useless, for they will become a fearful
and intolerable nuisance, spreading pestilence and death all over
the city.
In addition to this there is a project for sewage irrigation, at a
cost of close upon a quarter of a million sterling, the only stuff avail-
able being diluted soap-suds and dish-washings, and if this does not
succeed, he proposes to send the sullage back into harbour at Colaba,
but how it is to get there he leaves unexplained.
He also proposes a People’s Park near the mouth of his intended
sewer, which he himself says “may produce serious consequences.^
It is to be feared that the Municipal Commissioner has somewhat
prematurely adopted Captain Tulloch’s Report, from an earnest and
nafriral desire to get this most vital question settled, and the work
executed as quickly as possible.
Is. SOWERBY'S MEMORANDUM.
Let us now turn to that portion of Captain Tulloeh’s report, which
reviews the writer’s Memorandum on the Drainage of Bombay.
Captain Tulloch is quite right in supposing that the contour Map
of the Island was not in the possession of the writer when he drew
up his Memorandum. Plans of this kind are not readily accessible
to outsiders, and after in vain trying to obtain a sight of this map,
it was the intention of the writer to take an opportunity of making
a contour survey of Bombay at his leisure, chiefly because, like every
other scientific question, it was extremely interesting, and any little
trouble would have been fully and amply repaid;—fortunately Captain
Tulloch/’s report is accompanied with a map of this kind.
Having now obtained possession of this plan, and converted it
into a model map of the Island, all doubts as to the mode of dealing
with Bombay are at rest; and it may be interesting to Captain24
Tulloch to know that the writer will not be obliged to abandon any
one of the main principles laid down in his Memorandum, in order to
extricate himself from “the horns of a dilemma.” Had this contour
plan been available, the project detailed in the Memorandum might have
been more complete, but would not have been materially different.
Captain Tulloch's mode of reviewing the Memorandum is so con-
fused as to be almost, if not quite, unintelligible. It will be better
therefore to follow the original Memorandum rather than Captain
Tulloch* s report on it.
The Memorandum proposed to intersect the Island with one main
Canal, and Branches, the water from the canal to be made available
for flushing the sewers.
If we look at the Model Map of the Island, which clearly shows
that there is an immense tract of low-lying swampy ground, occupy-
ing 4J square miles of surface, and liable to floods during every
monsoon, the question arises how is that ground to be reclaimed and
rendered free from moisture. Captain Tulloch proposes to get rid
of the floods by means of sluices and expensive pumping engines ;
at the same time he objects to the land being raised, but prefers
keeping it as a safety valve for the floods of Bombay. Now the cost
of permanently raising such a large area even a few feet, with earth
brought from a distance, would be so great as to prevent its being
ever accomplished, and the alternative of allowing it to remain as a
swamp is as objectionable as it well can be, and Captain TullocliAs
mode of treating the matter is of more than doubtful practicability;
we are therefore obliged to have recourse to some other alternative.
If we refer to other localities similarly situated, we shall find plenty
of examples how the work of drainage has been accomplished,
namely, by cutting open canals right through the lowest lying ground,
with branches to the right and left. In some places, as in St James’s
and the Regent’s Parfcs in London, which were formerly swampy,
the drainage has been accomplished by digging out large sheets of
ornamental water, and in the Peopled Park in Madras (if it ever
were a swamp) a similar method has to some extent been followed;
and possibly, a like plan might be advisable on the Flats at Bombay,
in order to retain a portion of the immense quantity of water that25
finds its way there during the monsoons. But it is believed that a
broad open canal would be preferable.
Captain Tulloch proposes an expenditure of £130,000 in sluices
and in extending the present old main drain. The imperfections
of this plan have already been pointed out, but it may be asked,
are not the water-ways which lead to these sluices (excepting the
underground drain) incipient canals, of no possible use except for
a very few days in the year during the floods ?
It is immaterial whether we raise the land by earthwork, or dig a
trench for the surface water to fall into, provided the moisture is got
rid of. Now the Flats of Bombay are surrounded on both the east
and west by high ground with one or two openings. On the Model
Chart, the Flats have the appearance of a large inland lake, the
deepest part being in the middle of the Island; the only outlet is to
the north and south. The lowest point is 47 above datum. This is
however, only a very small part of it; generally, it is 49 to 52. If
we lay out our canal with the bottom at 46 above datum, or a foot
above low water neap tides, it would then drain the very lowest
point in the Flats, which is 47 above datum, and it could be
emptied at low water neaps which is 45, and most effectually so at
low water springs which is 42*75 (I am assuming Captain Tulloch's
tide levels to be correct). At such a depth we should have an
average cutting of 5 or 6 feet throughout the low parts of the
Island. Having settled the level of the bottom of the canal, we will
now settle the level of the water at the surface of it. This, it is pro-
posed, should be 55 above datum, and as it has been shown that an
outfall for the sewers can be obtained at Love Grove at 48*5 above
datum, still leaving 3 feet 6 inches above low water neap tides, there
would be a clear head of water of 6 feet 6 inches, which would be
ample for all flushing purposes, and the surface of the canal would
still be two feet and a quarter below high water spring tides.
And now comes the explanation of that terrible dilemma on the
horns of which Captain Tulloch thinks he has put the writer. He
seems to forget that it is water that has to be dealt with, which
offers the greatest facilities for moving it from place to place, and not
solid inert matter like earth and stones. The smallest possible
variation of level will put the whole in motion; probably he is not26
aware tliat the New River, which has for many generations supplied
London with water, has only a fall of 3 inches per mile, and that the
bed of the lower part of the Thames itself, has only the same
inclination. But it is not at all necessary to put so fine a point as
this upon the levels for the drainage of Bombay; there is ample
variation in the contour of the ground to free the Island both from
surface and town drainage without any expensive system of
pumping; there is a difference of 25 feet between the portion of the
Island chiefly built upon, and low water neap tides, or 20 feet to
mean sea level.
During the whole of the hot and dry weather, the Canal which it is
proposed to run through Bombay, could be kept full, the level of 55
above datum or thereabouts being maintained; so soon as the mon-
soon floods set in, then the canal could be emptied, and thu's become
a catchwater channel for the floods, sluice-gates being opened at
various points to admit the rain water, and the sluice gates at the
several entrances kept going to exclude the tide, and to allow the
passage of the floods. The emptying of the Canal, during a few days
in the monsoon, would be no disadvantage, as the trade of the Island
is nearly at a stand-still during that time; it would Tbe a temporary
periodical inconvenience like the closing of the Elbe by ice in win-
ter, or the stoppage of a railway by a snow-storm; all the rest of the
year, the water in the canal would be available for flushing the sewers.
It is to be hoped that Captain Tulloch can now understand, that by
retaining the water in the canal at a high level during the dry
weather, and emptying it during the rains, it can be used both for
flushing the sewers, and draining the Island of floods, becoming in
fact a catch-water drain.
The water in the canal, Captain Tulloch says, would become
stagnant and a nuisance; but if the tidal levels put forward by him
are correct, this never need be so; for there is at spring tides
2\ feet more water than in the level of the canal, which could be
pent up at one or the other entrance basin; besides there is a clear 6^
feet available, part of which might be lowered at every tide, so as to
give a continuous flow of water in either direction.
Having explained away the difficulty which Captain Tulloch has
raised regarding the levels of the canal itself, it may be necessary27
to say something about the proposed intercepting sewers on each
side of it. The water in the canal can, as has already been shown,
be made available for flushing the sewers without any difficulty; it
is therefore desirable that these sewers should be as adjacent to the
canal as possible. But it does nit therefore follow that the sewers
need continue the whole length of the canal, at one uniform
inclination from beginning to end. In the Memorandum it was
stated that the Canal should have several outlets into the sea
and harbour; at each of these outlets, the sewers might also ter-
minate. Thus the sewers, while following the entire length of the
canal, would be divided into sections, each section having a distinct
outlet; nor need the whole of those sewers, especially those to the
northward, be constructed till the ground is occupied by buildings,
and they are actually required. It would be quite useless to enter
into all the details of these sewers, until the time arrives for carrying
them out; but it would not -be difficult to prepare the minutest par-
ticulars, and in such a way as to satisfy the most critical Engineer.
This would be giving a complete system of town drainage for the whole
ixf the Island, assuming it to be all covered with streets and houses.
Mr. Crawford does indeed say that Captain Tulloch’s scheme
drains the whole Island, and the city, present and future, whereas he
really only proposes to drain the present city by a main sewer taken
to Love Grove, and endeavours to get rid of the flood waters by
powerful pumping engines and sluices. This certainly is not drain-
ing the whole Island and city, present and future. *
Having disposed of Captain Tulloch^s engineering objections, let
us take a sanitary, commercial, and financial view of the subject.
As Captain Tulloch holds up his hands in horror at the idea of a
canal passing through the heart of Bombay, he will be unable to ap-
preciate the advantages that will be derived from a stream of pure
sea water such as the canal proposed would give; there are fortu-
nately many others who can do so. It h^s been shown that the water
would never become stagnant, but may be made to flow in either
direction, and if necessary, be repeatedly emptied and filled again, so
that there need be no apprehension on this head.
Captain TullocVs idea is that canals in Bombay would be worse
than useless, that they would in fact, be a serious evil; but if the28
proposed canals did nothing more than drain the 4£ square miles of
low ground near the Flats, according to Captain Tulloch’s own
report, they would be a great benefit to the Island, for at
page 9, he gives a very graphic description of that most insalu-
brious locality, which shows what a very serious source of disease is
constantly present in Bombay, so long as the Flats remain unre-
claimed. While writing upon this question, it was but natural that
Captain Tulloch should give examples from places with which he
was most familiar, so he compares the proposed canals with the
northern canal, and the river Coom at Madras. They say there is
but one step from the sublime to the ridiculous, and Captain Tulloch
has furnished an example. So far as is remembered, that receptacle
for eveuy kind of filth, the Coom river, has but little water in it for
about Ilf months out of the 12, and is absolutely dry for 9 or 10
months every year, and the northern canal is an incomplete work,
and therefore of very little use, being quite unconnected with the
Madras Harbour.
Some years ago there was a canal very like the one at Madras, in a
town on the west coast of England. The Trustees or Commissioners
under whose management it was, could make nothing of it, and it
was a continued source of squabbling and vexation. One day an
enterprising and intelligent contractor (who by the bye, could hardly
sign his name) saw the place, and offered the Trustees £4,000 for it.
This they readily accepted with many knowing looks at each other,
thinking they were making a capital bargain. The Contractor,
after getting possession, set about improving the canal, and con-
necting it with the nearest railway by a short branch. In a very
little time the canal had increased so much in value, that it was
worth 20 times what the Contractor had given for it, and whenever
he went into the town, he used to boast that he had not bought the
canal, he had found it, much to the disgust of his friends the Trustees.
Perhaps no such luck will befal the northern canal at Madras, but
as they are proposing a gigantic Breakwater to protect the harbour,
there is no saying what may happen.
If Captain Tulloch had compared the canals proposed in Bombay
with the Grand Surrey and the Regent’s Canal in London, or those of
Hamburg, and other large cities, the comparison would have been29
better, and if lie had noticed the traffic on those silent highways, and
the immense amount of accommodation they afford to the localities
through which they pass, he would probably not so hastily have
given his opinion as to the superiority of Railways. Through densely
populated districts, every yard of water-frontage is invaluable;
can the same be said of any single Town Railway in existence ?
Take the North London Railway with its half dozen hideous coal
stages, or the South Eastern Line, with its long row of ugly arches
from *nine Elms to London Bridge, and Captain Tulloch will find,
that, though valuable for through traffic, they are of little or no use
to the densely populated neighbourhood through which they pass,
but on the contrary, are regarded as an intolerable nuisance, just as
the two Railways which enter Bombay, are regarded very lAich in
the same light.
If Captain Tulloch found it inconvenient to get about in Venice, as
he says he did, then he must have a singular partiality for walking,
for numberless Gondolas would have taken him across the Canals at
Vny (moment. What greater relief can be imagined than the still-
ness of the silent highways of Venice, after the dust, noise, and turmoil
of London, Paris, or Vienna !
What Captain Tulloch's experience of Bombay may be is uncer-
tain, but the writer has passed from one end of Venice to the other in
less time than it took him to get from the Pareli Road at Byculla, to
the Clarendon Hotel, which is only a few hundred yards distant ;
and this, not once, but many times, when the engines happened to
be shunting. No doubt others have experienced the same inconve-
nience.
Captain Tulloch also incidentally alludes to the Canals in Holland ;
we wonder what he would have done had he been a Dutchman !
Would he have reclaimed Holland with making Railways through the
country ? It is doubtful whether George Stephenson, the pioneer of
railways, would have done this, though he containly did reclaim
Chatmoss ; but this was high table land, only requiring to be drained.
That it is not possible to drain the Flats of Bombay by means of
railways is evident, for there are two running right through them
already, and if Captain Tulloch's datum as to the height of those floods30
be correct, they must have been under water to a great extent
during last monsoon. Each of these railways lias an incipient canal
along the sides of them, made by excavation for the embankments
on which they are built.
Independent of any use these Canals may be, for either flushing
the sewers, or draining the Island, it is necessary to show that the
proposed expenditure would be justified on commercial grounds.
It will readily be admitted that a waterside frontage is of some
use and value for trade, whether the frontage be a navigable river or
a canal. In London and other large cities, plenty of examples of
this kind can be found ; and though railways have in some measure
supplemented canals, and are a quicker means of conveyance for
through traffic, they are not cheaper; this is too well known to
require any proof.	9
London has, it is true, recently curtailed its river frontage, by
building Embankments or Boulevards in imitation of Paris ; but as
London is a sea-port, and Paris is only a large inland town, the
effect of this in London has been to drive the trade of the place tv^
other localities, and canals have been projected to supply the lost
wharfage ground between Westminster and Blackfriars Bridges;
whereas a very slight modification of the Thames Embankment
would have completely obviated this.
Bombay, we all know, aspires to be the Capital of India, its
splendid Harbour giving it obvious advantages; and if railways
do not render the place untenable, and the zealous advocates
of Reclamation do not quite ruin the Harbour, which they bid
fair to do, having already made the low-water line recede half a
mile, then there can be no doubt that Bombay will become the
Commercial Capital of India, though the seat of Government may
still remain fixed at some remote place like Calcutta, or quiet place
such as Simla, just as the American Government prefers to remain
at Washington. But when the Great Indian Peninsula Railway is
completed throughout, connecting Bombay with Madras and Calcutta,
and when Central India, the North West Provinces, and the Pun-
jaub, are opened out by the Baroda line, which they unquestionably
will be in a few years, notwithstanding present delays,—then will
Bombay become a place of such vast importance, as at present we31
can but little conceive ; and it is with, a view of accommodating the
enormous trade that will then pour into Bombay, that the Canals
were first proposed, inasmuch as they could be made now at a mo-
derate expense, the ground being comparatively unoccupied. A few
years hence it will be covered with buildings of one sort and
another.
The entire length of Harftour Frontage is very limited; the effect
of these Canals wo aid be practically to extend the harbour frontage,
into and through the middle of the Island. No more erroneous idea
was ever entertained than that the Elphinstone Land would be suf-
ficient to accommodate all the trade of Bombay, when the Railways
were completed; those who have held such an opinion, muft have
but a feeble notion of what the trade will be. It is perhaps a mistake
ever to have allowed these Railways of Bombay to go nearer than the
Flats, where, when reclaimed, there would have been ample ground
for warehouses, with a branch running up to the Harbour and the
Fort for passengers and light traffic. But the Canals now pro-
posed should have been the means of communicating with the har-
bour ; had the Railway Stations and Warehouses been so placed,
they would have been secure from all danger in the not impossible
event of the Harbour being attacked by an enemy.
Look for example at the Railways in London, the Great Western
with its Goods Station at Paddington, the North Western at Camden
Town, the Great Northern at King's Cross ; all these lines are, it is
true, connected by branches with the Port of London, but the Canals
also dispose of much of their traffic.
Contrast the convenience to the trade of Bombay, of a Canal con-
nected with the Railways at one end and the Harbour at the other,
and then conceive the confusion that would ensue with all the export
traffic of the railways terminating in Bombay, meeting the import
trade along the very limited foreshore of the harbour, or as some
one has suggested, all concentrated at the Elphinstone Land
Company's Grounds, feebly assisted by Tidal Basins.
Whenever this subject of Canals has been discussed with those
who understood the present and future wants of Bombay, there has
been but one opinion, and that a most favourable one. The idea of32
these Canals is probably not a new one, for let any one take the
trouble to examine the ground, and when he sees the numerous
pools of water along the route proposed, particularly those broad
ditches or incipient canals on each side of the Railways, he is
certain to arrive at the same conclusion.
Let us now examine the probable cost of the proposed canals.
The actual length would be about 9 nUles, the greater part passes
through swampy or agricultural land, and consequently is not of
very high value; a very small portion indeed would pass through
Town land of any high value; the cost has therefore been assumed at
2J lakhs or £25,000 per mile, which is greater than the cost of any
railway yet constructed in India. This would give
For 9 miles............................... £225,000’
Add to this 6 outlets with works.......... „ 120,000
And the Drainage.......................... ,, 125,000
£470,000
or say in round numbers half a million sterling, as against Captain
Tulloch's scheme, which is to cost three-fourths of a million.
Most of the work of the Canals is such that an intelligent navvy
or a Madras Wuddah would do it without asking many questions;
how therefore Captain Tulloch contrives to make it 150 or 200 lakhs
surpasses comprehension; most of the Canal work would be through
alluvial soil, which the writer is now getting done at from 10 to
12 annas per brass of 100 cubic feet, and would be a high rate at
one rupee, and if the Canal were 9 miles long, 200 feet wide, and
10 feet deep, we should have—
Cubic feet,
5,280 X 9 X 200 X 10 =	950,40,000
Rs.
At 1 Rupee per 100 feet...........................	9,50,400
Say 20 Bridges of 200 feet, at Rs.	120 per foot. 4,80,000
Wharves and other works ..........................	5,00,000
Contingencies 10 per	cent.......	1,93,040
21,23,440
or only £212,344 sterling, instead of £225,000.33
If we take the expenditure proposed to be incurred by Captain
Tulloch, only .one half of it can be said actually to appertain to the
drainage proper of the city, the other half being an outlay, partly for
getting rid of the surface water, which is troublesome for a very small
part of the year, and only excessive once in twenty years, the
balance being applied for an irrigation project, which, if experience
be any guide, is sure to end in failure.
Most countries are subjected to heavy floods at times, but in India
they are always confined to one period of the year, and that a very
short one. They resemble snow-storms in colder latitudes, but no
one has ever proposed to put London or Vienna under a glass case,
because such snow-storms are of very limited duration; and the mon-
soon floods ought to be regarded in much the same light.
Had Captain Tulloch proposed a large expenditure for excavating
a tank on the Flats, for retaining some portion of the 520 millions of
cubic feet of water, which he says falls into the low grounds, and
which he proposes to eject in 24 hours, then one could have appre-
ciated his project much better, but no such proposal adorns his
report. Yet one would have imagined that, acquainted as he is with
Madras, and the splendid tanks scattered over the country there,
some such idea would have suggested itself to him; for though the
water might not have been pure enough for drinking, it would have
answered well for many other purposes, such as watering streets,
flushing drains, washing clothes, and other domestic uses. Has
Captain Tulloch never seen the Hampstead Ponds, nor the Reservoirs
at Stoke Newington ?
Captain Tulloch says it would be a sad day for the inhabitants o
Bombay which should see the introduction of Canals into it; bu
there is a sadder picture for that City than Canals, and that is, whei
its splendid Harbour is rendered as useless and shallow as Basseii
and Goa, by some of those Engineers whom Captain Tulloch hai
evidently taken into his confidence and consulted, and when one-hal
of the Island is literally poisoned by a system of telescopic pipe
drainage, and the other half rendered unbearable by sewage-manure
irrigation.34
The contrast between two such pictures as the large Commercial
City with its magnificent Harbour, and splendid Canals, and a har-
bour ruined by reclamations, and the Island turned into a large
garden, that can only produce unwholesome vegetation, is so great,
that the decision of Bombay's Future may be safely left to the
judgment of those whose interest it is to determine the question.
The saving alone by the canals, in the cost of metalling the roads,
and the wear and tear of vehicles, would almost pay the interest of
the capital embarked in the Canals.
The Municipal Commissioner has evidently adopted Captain
Tulloch's report somewhat too hastily, and the writer earnestly
recommends a further careful consideration of this most important
subject to Mr. Crawford, the Justices of Bombay, and the Govern-
ment ; because if the City be handed over to the tender mercies of
Captain Tulloch, and his scheme carried out, the results will be most
disastrous both in a sanitary and financial point of view, and to use
liis own words “ it will be a very sad day indeed for the inhabitants
of Bombay;” whereas if the project now advocated should b^>
adopted, it would be a noble monument of Engineering for all time.
WILLIAM SOWEEBY, C.E., F.G.S., Ac.
Surat, December, 1868.35
APPENDIX,
Remarks on the Cleansing, Purifying, and Ventilating of
Common Sewers, with a proposed new system for Purify-
ing and Ventilating them.
Great expense lias already been incurred in the metropolis, and
Introduction and general other large towns and cities, for the purpose
observations.	0f improving, purifying, and cleansing com-
mon sewers, drains, and other channels, in order to carry off the
foul water and refuse from the dwelling-houses and streets. It is
a subject which has long occupied the attention of many scientific
rap.d practical men. And at a time when disease is so prevalent it
becomes a matter of very great and vital
-pi i r v . importance, because this disease is found
Prevalence 01 disease m 1	3
localities badly drained. chiefly to occur in localities which are
imperfectly drained and cleansed.
Though the filth that accumulates and chokes up the sewers and
cesspools may have been removed by the
Accumulation of filtn,	r	J	#	^	J	J
and removal by flushing, usual means of flushing, pamping, and hand-
&c’	labour,	which is rendered easy of accomplish-
ment where there	is	a sufficient	supply of water, and a proper system
of sewerage; yet the purifying and venti-
Supply of water.	.	-■
ting of sewers requires to be attended to as
No ventilation.	11	iri	■.	,,	.	n	,
well;	and, although this does not appear
to have been	quite	lost sight	of, it is still, up to the present time,
altogether unprovided for.
A proper system of sewerage not only supposes the sewers to be
^	.	well	cleansed,	but	also	well	purified and ven-
Proper system of sew- ^	3	.	.
erage should not be im- tilated. Sewers have no right to be in an
pure at all.	impure	state, either from the accumulation
of foul matter or noxious vapour.36
It	may	be	supposed	that the removal of the filth would also re-
move the stencli arising therefrom, but ex-
Removal of filth does perince proves that this is not the case •
not remove ioul air.	r	■	,
because during the passage of the filth along
the sewers	a	quantity	of impure air is generated, which gradually
accumulates.
And, therefore,	notwithstanding	all that may be done in the way
of flushing	and cleansing, it is evident that
Foul air still remains.	.	,, ,.	P .
there is at	all times an accumulation 01 im-
pure air which is not removed.
That this impure	air must find vent, To endeavour to confine
it in the sewers underground, would be quite
Foul air must escape.	useless and impossible; it being lighter than
i? oui air rises.
common air, it will ascend.
That there is no regular plan or system provided for its escape.
No plan for escape.	That it must, therefore, escape through
Irregular escape.	some irregular and imperfect channel.
That to allow it to escape in its impure state through any channel,
Impure air destructive either imperfect or otherwise, is very dan-
to hfe.	'	gerous	and	destructive	to	life	and	health.
Means of escape	usua^ means by which it makes its
# escape, are :—
,T «	Out	at	the	mouths	or	outfalls	of the
Mouths or sewers.
sewers.
Grates	Up the grates into the streets, courts,
alleys, &c.
Sinks.	And through the sinks into the houses.
„ ,, x.	A	,	And thus mingling with, and polluting
Polluting atmosphere.	do	r	o
the surrounding atmosphere.	#
But whenever the mouths of the sewers are choked up by the Bowing
Mouths of sewers stop-	of t]ie tide> as hJ tlie Rive]V Thames in the
ped up by flowing of tide metropolis, the impure air is then driven
finds vent up sinks* &c.	_
back, and becomes compressed, or otherwise
finds freer vent, and in larger quantities, up the grates and sinks
into the streets and houses.37
Also, when the wind blows into the outlet of a sewer, or in an
™ p . i i • opposite direction to its course, the impure
Blowing of wmd drives	.
up foul air.	air is in the same manner driven back into
the houses, &c.,	as when the tide flows.
Stench traps have been invented for	preventing tbe impure air
from rising into	the streets ; and flaps have
Stench traps.	been added to the	side drains	for keeping
Flaps not efficient.	.	.
Coniine it in one place.	it from passing	into the houses; these are,
Escapes elsewhere or re-	doubtless, very	useful, but are not of them-
mains m sewer.	.
Rushes up in a dense	selves sufficiently	effectual, for	they confine
V°S“er returns into sewer.	the imPure ^ in	one Place> and comPel
to find vent in some other, or	otherwise it
remains in the sewers until it has become more obnoxious; and,
whenever a trap is opened, it rushes up in a dense volume, poisoning
the surrounding air; but when once it has found vent, it is very cer-
tain that it will never return again into the sewers.
It is not the presence only of impure air in sewers which is so
c	dangerous, it is its continued accumulation
ouSACCUmUlati°n iS danSer'	for a length of time 5 whicl1 sllould be Pre-
vented by a proper system.
The ventilation of a building, by means of large fans, with flues
for consuming the vitiated air, can be ac-
%nsllandfluesbmldmgS’	complished, provided the surrounding
atmosphere is sufficiently pure; but in all
large towns this is quite impossible, until the sewers are perfectly
ventilated, and free from all impurities.
The ventilation of coal mines has been brought to a great de-
Coal mines	£>re® Pei>fection, and, where sufficient
precaution is used for removing the foul air
or gas, accidents by explosion, &c., are prevented; but in this case
there is but one means for its escape, that is at the mouth of the pit.
,	The chief object to be attended to, there-
Escape at mouth only.	J
fore, is to prevent the accumulation of foul
air as «oon as it is discovered to exist, by conveying it from the
source whence it arises out at the pit's mouth, and by forcing down
a sufficient quantity of fresh air to supply its place.38
The plan usually adopted for ventilating the interior of a vessel,
is by tying up a windsail, which catches the
Ventilation of a vessel •	-j •	1	.	,°	•,	n	.,T
by windsail.	wind, and it drives down into the hold with
^ Foul air escapes impure, great force, expelling the impure air, and
effectually purifying and ventilating the
vessel; in this case, however, the impure air only escapes to vitiate to
a certain extent the surrounding atmosphere.
But the underground drains of a large town lay so near the surface,
the impure air confined in them is so dense,
buildfngs &c dlfferent t0 and the channels for its escape are so nu-
merous, and so complicated and irregular,
that it is impossible to deal with them as with a building, a mine, or
a vessel.
It is, therefore, proposed to adopt an entirely new system for
purifying and ventilating sewers, by means
Proposed plan for ven- f	^ impure air may be allowed to
tilating sewers.	r	J
escape through a regular channel, and its
place be supplied by a continual stream of fresh air.
PROPOSED PLAN.
The Plan proposed for Purifying and Ventilating Sewers is as
follows :—	11
1st*—To have air shafts with tops for receiving the wind and throw-
. „	, . .	ing down a stream of pure air into the
Air shafts for admission.
sewers.
2nd.—To hate chimneys communicating
Chimneys for escape.	with the sewers to allow the impure air to
escape.
3rd.—To supply a stream of disinfecting fluid, or a jet of Chlorine
Stream of disinfecting gas>for mingling with and purifying the
fluid or gas.	impure air as it escapes up the chimneys.
The details for carrying out this Plan are shown by the accompany-
ing Drawing.39
¿DESCRIPTION OF DRAWING, to.
The Drawing shows two Plans, one for having the air shafts and
chimneys placed immediately over the sew;ers;
Air shafts and chimneys, the other showing them at the side of the
Street, or in any vacant space adapted for the purpose, having a com-
munication with the main sewers. The air
Situation.	shafts	and chimneys to be a convenient
distance apart.
On the top of the air-shaft is shown a self-adjusting cap of an ear
shape, or any other similar and approved
shaft f"a^UStm^t0P °f aif" f°rm f°r receiving the largest volume of
wind might be adopted, which, driving into
the top will rush down the shaft into the sewer with great velocity,
forcing before it the foul air until it reaches the escape chimney, up
which it will ascend, being of a lighter nature than common air; in
^	, .	.	.	ascending up this chimney to be made to
% Phlorme gas mixing	°	r	J
with inSpure air renders it pass through a continued flow of chlorine
pure'	gas, which, mingling with the foul air or
sulphuretted hydrogen, will decompose and render it pure.
The chlorine gas to be supplied from Chlorine Gas Works by
Chlorine Gas Works	main pipes running along the inside of the
sewers ; thus if there should be any escape
of gas it will not be wasted, as it wilfl partially destroy the foul air
in the sewers; cocks to be provided for regulating the supply of gas,
or shutting it off when not required.’
The shafts and chimneys to be provided with throttle valves, by
which they can be closed at intervals when
Throttle valves.	,,	.	« ,.	,	.	,	n	^
the disinfecting agent is not used. On
opening the valves the air will rush down the shafts and along the
sewers.
Above the throttle valve, in the escape chimney, a kind of tubular
Tubular grating.	grating is shown for supplying the chlorine
Wire gauze cap to chim- gas; and on the top of the chimney is placed
ney‘	a cap of wire gauze, to prevent particles of
impure matter from ascending out of the sewers into the open air.40
' b
A Plan is also shown for converting the lamp posU into air shafts
- ,	, and escape chimneys. Everir alternate lamp
Plan for lamp posts as	r	17	J	r
air shafts and escape chim- post to be provided with an ear-shaped self-
neys*	adjusting	top for the admission of pure air,
and every other lamp post to be provided with apparatus for supply-
ing a jet of chlorine gas issuing out of a perforated globe with a
throttle valve beneath, the supply being regulated by a cock.
Yalve and cock opened ^e valve and cock may be so connected
by one key.	together as to be opened and shut by one key.
The top of the lamp post for escape to be covered with wire
gauze.
In order to render the whole effectual, a regular system of cleans-
ing and flushing must be kept up; and it
iirreqS-ertem ^flU<h' is supposed that the air rushing down the
shafts and along the sewers will cause an
agitation in the water flowing down*the sewer, and thus render the
flushing more complete.
By a propel* arrangement, all high columns, as the Nelson Column
and Monument, might be adapted as air
Monument and Nelson’s shafts or chimneys, thus rendering them
Column, as air shafts, &c.	>	,	t	-p
T j.1	,	r	i	i	useful	as	well as ornamental. And if once
Little trouble when
system is established. * this system was properly established and
efficiently carried out, it would require but
little trouble to keep the air in sewers free from noxious smells,
which pollute the atmosphere of towns and cities, and which spread
pestilence, disease, and mortality.
WM. SOWERBY, Jun., C.E., &c.
52, Parliament Street, Westminster,
December, 1848.
BOMBAY : PRINTED AT THE EDUCATION SOCIETY'S PRESS, BYCULLA.